SRAC8

AC Input Step Motor Drive

User Manual
Rev. 1.1

AMP & MOONS’ Automation

 SRAC8 User Manual

Contents
1 Introduction................................................................................... 3
1.1 Features..............................................................................................3
1.2 Block diagram.....................................................................................4
2 Mounting the Drive....................................................................... 4
3 Connections................................................................................. 5
3.1 Connecting to Power..........................................................................6
3.2 Connecting to a Motor........................................................................7
3.3 Connecting the Inputs and Outputs....................................................8
3.3.1 Step & Direction Inputs...............................................................................8
3.3.2 EN input......................................................................................................9
3.3.3 Fault Output..............................................................................................10
4 Switch Selection......................................................................... 11
4.1 Microstep Resolution........................................................................ 11
4.2 Running Current...............................................................................12
4.3 Idle Current.......................................................................................12
4.4 Anti Resonance.................................................................................13
4.5 Step Input Mode...............................................................................13
4.6 Step Input Signal Filter.....................................................................13
4.7 Step Smoothing Filter.......................................................................13
4.8 Self Test............................................................................................13
5 Motor selection........................................................................... 14
5.1 Recommended motors.....................................................................15
5.2 Torque-Speed Curves ......................................................................15
6 Error Codes................................................................................ 16
7 Reference Materials................................................................... 16
7.1 Mechanical Outline...........................................................................16
7.2 Specifications....................................................................................17
7.2.1 Electrical Specifications............................................................................17
7.2.2 Environmental Specifications...................................................................17
8 Contacting MOONS’................................................................... 18

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1 Introduction
Thank you for selecting the MOONS’ SRAC8 Step Motor Drive. The SRAC8 series AC input drives
are based on advanced digital current control technology and provide high torque, low noise and
low vibration. Many of the operational paramteres are switch selectable. We hope our dedication
to performance, quality and economy will make your motion control project successful.

1.1 Features
• Advanced digital current control provides excellent high speed torque
• Auto Setup measures motor parameters and configures motor current control and anti-
resonance gain settings
• Uses universal AC input 80 to 265 VAC
• Speed Range - up to 50 rps
• Microstep Resolution - switch selectable, 16 settings: 200, 400, 800, 1600, 3200, 6400,
12800, 25600, 1000, 2000, 4000, 5000, 8000, 10000, 20000, 25000 steps/rev
• Running Current - peak setting, switch selectable, 16 settings: 0.4, 0.6, 0.9, 1.2, 1.5, 2.0, 2.5,
3.0, 3.5, 4.0, 4.5, 5.2, 5.9, 6.6, 7.3, 8.0A
• Idle Current - automatic reduction of running current 1 second after the motor stops, switch
selectable, 4 settings: 25%, 50%, 70%, 90% of running current
• Anti Resonance - raises the system-damping ratio to eliminate midrange instability and allow
stable operation throughout the speed range of the motor, switch selectable, 4 settings for low to
high inertia loads
• Control Modes - Step/Direction pulse input or CW/CCW pulse input, switch selectable
• Input Signal Filter - filters out unwanted noise that can cause extra steps, switch selectable,
2MHz or 150KHz
• Step Smoothing Filter (Microstep Emulation) - performs high resolution stepping by
synthesizing coarse steps into fine micro-steps, switch selectable, ON or OFF
• Self Test - performs a 2 rev, 0.5RPS, CW/CCW move test, switch selectable, ON or OFF
• Motor Selection - a 16 bit rotary switch is used to select the desired motor database which is
pre-loaded at the Factory

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1.2 Block diagram

Universal AC Input Power

80 to 265 VAC Supply

5V 15V
switching reg
reg

SRAC8
Block Diagram
3.3V
reg Voltage
Det.

Gate MOSFETs
Drivers (8) motor
Motor Selection Rotary (4)
switch

STEP/DIR/EN Optical
FAULT Isolation DSP
Microstep
Over
Idle Current
Current
Run Current Det.
Load Inertia Settings 16-bit
Input Signal switch LED
Signal Filter
Smoothing Filter
Self Test

2 Mounting the Drive

The SRAC8 drive can be mounted only on the narrow side of the chassis. M4 screws should be
used in the two holes at the back of the drive.

The amplifiers in the drive generate heat. To operate the drive continuously at maximum power
forced air cooling, as from a fan, should be provided.

Never use the drive in a space where there is no air flow or where other devices can cause the
surrounding air to be more than 40 °C. Never put the drive where it can get wet or where metal
particles can fall into it.

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3 Connections
To use the SRAC8 Step Drive, the following items are needed:

• Universal AC input of 80 to 265 VAC

• Pulse & Direction signal
• A compatible step motor

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3.1 Connecting to Power

Use the supplied connector to connect to the AC supply according to the diagram below. Use 16
AWG wire for Line (L) and Neutral (N). Use 14 AWG for Earth Ground (G).

Care should always be taken when working with high voltages.

In regions where the single-phase supply is higher, an auto transformer can be used to drop the
voltage to the correct level.

The SRAC8 contains an internal 10A fast acting fuse.

Earth Ground (green)

Neutral (white)
Line - hot (black)

Regeneration Clamping Circuit

High speed motion generates high voltage which can be transferred to the drive during rapid
deceleration, and the drive may indicate an over-voltage error condition after stopping from a
high speed motion. The SRAC8 has regeneration clamping circuitry with an internal 200ohm 10W
resistor. To protect the drive in a high speed, high load inertia application MOONS’ recommends
connecting an external 80ohm 80W resistor to the regen connector located on the side of the
SRAC8 drive.

External Resistor Connector

Housing: 39-01-3028(MOLEX)
Crimp: 39-00-0038(MOLEX)

Optional Accessories
Regen Resistor Kit
Part Number: REG80W80

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3.2 Connecting to a Motor

Motor connections should be made according to the following diagrams.

White
A White A
Green Brown
Green
Brown
Yellow C
C
Yellow
Gray B
Gray Blue Red
Pink
B Blue
Pink
D
Red D

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3.3 Connecting the Inputs and Outputs

3.3.1 Step & Direction Inputs
The SRAC8 Step Drive has two high speed optically isolated inputs called STEP and DIR. They
accept 5 to 24 volt single-ended or differential signals, up to 2MHz. The maximum voltage that can
be applied to the input is 28V.

The motor executes one step when the STEP input closes.

The direction of rotation is controlled by the DIR input state. A closed input (logic “0”) will result in
clockwise rotation, and an open input (logic “1”) will result in counterclockwise rotation.

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3.3.2 EN input
The EN input enables or disables the drive amplifier. It is an optically isolated input that accepts
a 5 to 24 volt single-ended or differential signal. The maximum voltage that can be applied to the
input is 28V.

When EN input is closed, the driver amplifier is deactivated, all the MOSFETs will shut down, and
the motor will be free. When EN input is open, the drive is activated.

When the drive has encountered an error and the fault is removed from the system, a falling signal
into the EN input will reset the error status and activate the drive amplifier again.

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3.3.3 Fault Output

The FAULT Output is optically isolated. The maximum collector current is 100mA, and the
maximum collector to emitter voltage is 30 volts. The output can be wired to sink or source current.

When drive is working normally, the output is open. When the drive encounters an error, the output
closes.

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4 Switch Selection
Many of the operational parameters of the SRAC8 can be set or changed by position switches -
either by a single switch or a combination of ON/OFF settings of 2 or more switches.

SW1 SW2 SW3 SW4 SW5 SW6 SW7 SW8

Microstepping Running Current

SW9 SW10 SW11 SW12 SW13 SW14 SW15 SW16

Idle Current Anti Resonance Step Input Mode Smoothing Filter

Step Input Signal Filter Self Test

4.1 Microstep Resolution

The microstep resolution is set by the SW1, SW2, SW3 and SW4 switches. There are 16 settings.

Microstep(steps/rev) SW1 SW2 SW3 SW4

200 ON ON ON ON
400 OFF ON ON ON
800 ON OFF ON ON
1600 OFF OFF ON ON
3200 ON ON OFF ON
6400 OFF ON OFF ON
12800 ON OFF OFF ON
25600 OFF OFF OFF ON
1000 ON ON ON OFF
2000 OFF ON ON OFF
4000 ON OFF ON OFF
5000 OFF OFF ON OFF
8000 ON ON OFF OFF
10000 OFF ON OFF OFF
20000 ON OFF OFF OFF
25000 OFF OFF OFF OFF

1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4

1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4
1 2 3 4
SW1
SW2
SW3 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4
SW4

1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4

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4.2 Running Current

The output current is set by the SW5, SW6, SW7and SW8 switches. There are 16 settings.

Current (Peak) SW5 SW6 SW7 SW8

0.4A ON ON ON ON
0.6A OFF ON ON ON
0.9A ON OFF ON ON
1.2A OFF OFF ON ON
1.5A ON ON OFF ON
2.0A OFF ON OFF ON
2.5A ON OFF OFF ON
3.0A OFF OFF OFF ON
3.5A ON ON ON OFF
4.0A OFF ON ON OFF
4.5A ON OFF ON OFF
5.2A OFF OFF ON OFF
5.9A ON ON OFF OFF
6.6A OFF ON OFF OFF
7.3A ON OFF OFF OFF
8.0A OFF OFF OFF OFF

5 6 7 8 5 6 7 8 5 6 7 8 5 6 7 8
0.4A 0.6A 0.9A 1.2A

5 6 7 8 5 6 7 8 5 6 7 8 5 6 7 8
5 6 7 8 1.5A 2.0A 2.5A 3.0A
SW5
SW6
SW7 5 6 7 8 5 6 7 8 5 6 7 8 5 6 7 8
SW8 3.5A 4.0A 4.5A 5.2A

5 6 7 8 5 6 7 8 5 6 7 8 5 6 7 8
5.9A 6.6A 7.3A 8.0A

4.3 Idle Current

The running current of the SRAC8 drive is automatically reduced whenever the motor isn’t moving.
The SW9 and SW10 switches control the percentage of the running current the idle current is
reduced to. The 90% setting is useful when a high holding torque is required. To minimize motor
and drive heating it is highly recommended that the idle Idle SW9 SW10
current reduction feature be set as low as the application 25% ON ON
can tolerate. 50% OFF ON
70% ON OFF
90% OFF OFF

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4.4 Anti Resonance

The SW11 and SW12 switches select the load Option SW11 SW12 Inertia
inertia. There are 4 settings. The inertia selection 0 ON ON Low
can help the SRAC8 drive to calculate the current 1 OFF ON
control parameter. If the load inertia is close to 2 ON OFF
that of the motor rotor, the low setting should be 3 OFF OFF High
selected. If the load inertia is higher than that of the
rotor, a proportionally higher setting should be selected.

4.5 Step Input Mode

Most indexers and motion controllers provide motion commands in the Step and Direction format.
The Step signal pulses once for each motor step and the Direction signal commands direction.
Some PLCs use a CW/CCW command signal: one signal pulses once for each desired step in the
clockwise direction (CW Step), while a second signal pulses for counterclockwise motion (CCW
Step). In the CW/CCW control mode, the CW signal should be connected to the STEP input and
the CCW signal to the DIR input.

Setting SW13 to OFF enables the Step & Direction format, the ON position enables the CW/CCW
format.
Note: The power must be cycled each time the position of SW13 is changed.

4.6 Step Input Signal Filter

The STEP and DIR signal inputs have a built-in digital filter to reduce the external noise. If the
system works on the low microstep, the 150 KHz setting should be selected. If the system works
on the high microstep, the 2 MHz setting should be used.

The SW14 switch selects the digital signal filter. ON sets it to 150 KHz, OFF sets it to 2 MHz.

Note: The power must be cycled each time the position of SW14 is changed.

4.7 Step Smoothing Filter

Command signal smoothing can soften the effect of immediate changes in velocity and direction,
making the motion of the motor less jerky. An added advantage is that it can reduce the wear on
mechanical components. SW15 selects this function - ON enables it, OFF disables it.

This function can cause a small delay in following the control signal, and it should be used with
that in mind.

Note: The power must be cycled each time the position of SW15 is changed.

4.8 Self Test

Setting SW16 to ON after the drive is powered up, will cause the drive to perform a Self Test move
of 2 revolutions both CW and CCW at .5 rps. Setting SW16 to OFF will disable this feature.

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5 Motor selection
Each position of the 16-bit rotary switch selects a different motor, and
automatically sets the configuration parameters in the drive. The SRAC8 drive
comes programmed with up to 16 typical motors as factory defaults. Drives
can be customized with specially selected motors when required.

When the motor selection is changed, the drive power supply will need
to be cycled.

Rated current
Switch Bit Motor Wiring
setting(A)
0 Series Connected 1.8
AM34HD0802
1 Parallel Connected 3.6

2 Series Connected 1.8

AM34HD1802
3 Parallel Connected 3.6

4 Series Connected 1.8

AM34HD2805
5 Parallel Connected 3.6

6 Series Connected 1.8

AM34HD4802
7 Parallel Connected 3.6

8 Series Connected 1.8

AM34HD6801
9 Parallel Connected 3.6

A Reserved

B Reserved

C Reserved

D Reserved

E Reserved

F StdMotor_119 4-lead Bipolar 5.8

Note: The rated current of motor is RMS value. The output current of MOONS’ drive is the peak
of sine value. Drive peak current = the rated current of drive * 1.4

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5.1 Recommended motors

Holding Rotor Motor
Length“L” Rated Current (A/Phase) Resistance(Ω/Phase)
Model Shaft Wiring Leads Torque Inertia Mass

mm N·m Series parallel Series parallel g·cm2 Kg

AM34HD0802-01 Single Shaft
66.5 3.0 3.4 0.9 1100 1.6
AM34HD0802-02 Double Shaft

AM34HD4802-01 Single Shaft 75 3.5 3.3 0.8 1350 1.9

1.8 3.6
AM34HD1802-01 Single Shaft
B(parallel) recommended recommended
8 96 5.0 3.6 0.9 1850 2.7
A(series) drive voltage drivevoltage
AM34HD1802-03 Double Shaft
220VAC) 110VAC)
AM34HD6801-01 Single Shaft 115 6.5 4.0 1.0 2400 3.5

AM34HD2805-01 Single Shaft

125.5 7.1 4.2 1.0 2750 3.8
AM34HD2805-03 Double Shaft

5.2 Torque-Speed Curves

AM34HD0802 AM34HD4802 AM34HD1802
Drive: SRAC8 1.8A(Rated Current)@ 220V
Drive: SRAC8 1.8A(Rated Current)@ 220V Drive: SRAC8 1.8A(Rated Current)@ 220V
Microstep：25000 steps/rev Microstep：25000 steps/rev Microstep：25000 steps/rev
3.0 3.5 6.0
2.5 3.0 5.0

T o rq u e ( N m )
2.5 .
T o rq u e ( N m )

T o rq u e ( N m )

. 2.0 . 4.0
2.0
1.5 3.0
1.5
1.0 1.0 2.0
0.5 1.5 1.0
0 0 0
0 10 20 30 40 50 0 10 20 30 40 50 0 10 20 30 40 50
Speed(rps) Speed(rps)
Speed(rps)

AM34HD6801 AM34HD2805
Drive: SRAC8 1.8A(Rated Current)@ 220V Drive: SRAC8 1.8A(Rated Current)@ 220V
Microstep：25000 steps/rev Microstep：25000 steps/rev
6.0 7.0

5.0 6.0
5.0
T o rq u e ( N m )

. 4.0
T o rq u e ( N m )

.
4.0
3.0
3.0
2.0
2.0
1.0 1.0
0 0
0 10 20 30 40 50 0 10 20 30 40 50
Speed(rps) Speed(rps)

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6 Error Codes
The SRAC4 Drive has two LEDs to indicate status. When the motor is enabled the green LED
flashes slowly, when the green LED is solid the motor is disabled. If the red LED flashes, an error
has occurred. Errors are indicated by combinations of red and green flashes as shown below:

Code Error
Solid green Motor Disabled
Flashing green Motor Enabled
3 red, 1 green Over Temperature
3 red, 2 green Bad Internal Voltage
4 red, 1 green Supply Voltage High
4 red, 2 green Supply Voltage Low
5 red, 1 green Over Current
5 red, 2 green Excess Regen
6 red, 1 green Open Motor Phase

7 Reference Materials
7.1 Mechanical Outline

54
120.5 10.5

SRAC
STEP MOTOR DRIVE RoHS
Motor Select

Serial No Part No

OUT - Microstep Table Current Table

OUT+ MSTEP SW1 SW2 SW3 SW4 Current SW5 SW6 SW7 SW8
EN - 200 ON ON ON ON 0.4A ON ON ON ON
400 OFF ON ON ON 0.6A OFF ON ON ON
EN +
800 ON OFF ON ON 0.9A ON OFF ON ON
DIR - 1600 OFF OFF ON ON 1.2A OFF OFF ON ON
DIR + 3200 ON ON OFF ON 1.5A ON ON OFF ON
6400 OFF ON OFF ON 2.0A OFF ON OFF ON
STEP -
12800 ON OFF OFF ON 2.5A ON OFF OFF ON
STEP+ 25600 OFF OFF OFF ON 3.0A OFF OFF OFF ON
1000 ON ON ON OFF 3.5A ON ON ON OFF
SW16 2000 OFF ON ON OFF 4.0A OFF ON ON OFF
SW15
177

162

4000 ON OFF ON OFF 4.5A ON OFF ON OFF

SW14
5000 OFF OFF ON OFF 5.2A OFF OFF ON OFF
SW13
SW12 8000 ON ON OFF OFF 5.9A ON ON OFF OFF
SW11 10000 OFF ON OFF OFF 6.6A OFF ON OFF OFF
SW10 20000 ON OFF OFF OFF 7.3A ON OFF OFF OFF
SW9 25000 OFF OFF OFF OFF 8.0A OFF OFF OFF OFF

SW8
SW7 Idle Current Anti Resonance
SW6 Idle SW9 SW10 Option SW11 SW12 Inertia
SW5 25% ON ON 0 ON ON Low
SW4 50% OFF ON 1 OFF ON
SW3
70% ON OFF 2 ON OFF
SW2
SW1 90% OFF OFF 3 OFF OFF High
SW13 Step Input Mode SW14 Step Input Signal Filter
B- ON CW/CCW ON 150K
OFF Step/Dir OFF 2M
B+ SW15 Smoothing Filter SW16 Self Test
ON Enable ON Enable
A- OFF Disable OFF Disable
GR=Green
A+ LED Codes RD=Red
MOTOR DISABLED SOLID GREEN
MOTOR ENABLED GR - GR - GR
OVER TEMPERATURE 1GR + 3RD
SUPPLY VOLTAGE HIGH 1GR + 4RD
N OVER CURRENT 1GR + 5RD
OPEN MOTOR PHASE 1GR + 6RD
L
INTERNAL VOLTAGE BAD 2GR + 3RD
SUPPLY VOLTAGE LOW 2GR + 4RD
EXCESS REGEN 2GR + 5RD
Made in China

4.5
Unit:mm

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7.2 Specifications
7.2.1 Electrical Specifications

Electrical Specifications
Parameter Min. Typ. Max. Unit
Power Supply Universal AC input 80 - 265 VAC
Output Current (Peak) 0.4 - 8.0 amps
Step Frequency 2 - 2M Hz
STEP Minimum Pulse Width Hi and Low 250 - - ns
DIR Minimum Pulse Width 62.5 - - us
Under Voltage Protection - 80 - VAC
Over Voltage Protection - 295 - VAC
STEP/DIR Input Signal Voltage 4.0 - 28 V
OUT Maximum Output Current - - 100 mA
OUT Maximum Output - - 30 V

7.2.2 Environmental Specifications

Environmental Specifications
Heat Sinking Method Natural cooling or fan-forced cooling
Surrounding Air Conditions Avoid dust, oily mist and corrosive air
Operating Temperature 0 - 40°C (32 - 104°F)
Maximum Ambient Humidity 90% non-condensing
Shock 5.9m/s² maximum
Storage Temperature -10 - 70°C (14 - 158°F)

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8 Contacting MOONS’

Customer Service Center

400-820-9661
MOONS’ Headquarter
168 Mingjia Road, Minhang District, Shanghai
201107, P.R. China

Domestic Offices North America Company

Shenzhen MOONS’ INDUSTRIES (AMERICA), INC. (Chicago)
Rm.401, Building 53, Zhongchuang Park, Jiyue City, No.13, 1113 North Prospect Avenue, Itasca, IL 60143 USA
Xinyi 5th Road, Taoyuan Street, Nanshan Dist, Shenzhen
MOONS’ INDUSTRIES (AMERICA), INC. (Boston)
518000, P.R. China
36 Cordage Park Circle, Suite 310 Plymouth, MA 02360 USA
Beijing
APPLIED MOTION PRODUCTS, INC.
Room 1206, Jing Liang Mansion, No.16 Middle Road of East,
404 Westridge Dr. Watsonville, CA 95076 USA
3rd Ring, Chaoyang District, Beijing 100022, P.R. China
LIN ENGINEERING, INC.
Nanjing
16245 Vineyard Blvd., Morgan Hill, CA 95037 USA
Room 1101-1102, Building 2, New Town Development
Center, No.126 Tianyuan Road, Moling Street,
European Company
Jiangning District, Nanjing 211106, P.R. China
MOONS’ INDUSTRIES (EUROPE) S.R.L.
Qingdao Via Torri Bianche n.1 20871 Vimercate(MB) Italy
Room 1710, Zhuoyue Tower, No.16 Fengcheng Road,
Shibei District, Qingdao 266000 P.R. China AMP & MOONS’ AUTOMATION (GERMANY) GMBH
Börsenstr. 14
Wuhan 60313 Frankfurt am Main Germany
Room 3001, World Trade Tower, 686 Jiefang Avenue,
Jianghan District, Wuhan 430022, P.R. China South-East ASIA Company
Chengdu MOONS’ INDUSTRIES (SOUTH-EAST ASIA) PTE. LTD.
Rm. 3907, Maoye Plaza, No.19, Dongyu Street, 33 Ubi Avenue 3 #08-23 Vertex Singapore 408868
Jinjiang Distrit, Chengdu 610066, P.R. China
Japan Company
Xi’ an
Room 1006, Tower D, Wangzuo International City, MOONS’ INDUSTRIES JAPAN CO., LTD.
1 Tangyan Road, Xi’ an 710065, P.R. China Room 602, 6F, Shin Yokohama Koushin Building,
2-12-1, Shin-Yokohama, Kohoku-ku, Yokohama,
Ningbo Kanagawa, 222-0033, Janpan
Room 309, Tower B, Taifu Plaza, 565 Jiangjia Road,
Jiangdong District, Ningbo, 315040, P.R. China India Company

Guangzhou MOONS' INTELLIGENT MOTION SYSTEM INDIA PVT. LTD.

Room 4006, Tower B, China Shine Plaza, 9 Linhe Xi Road, Rm. 908, 9th Floor, Amar Business Park,
Tianhe District, Guangzhou 510610, P.R. China Tal. Haveli, Baner, Pune-411045, Maharashtra, India

Chongqing
Rm. 2108, South yuanzhu Buliding 20, No.18 Fuquan Rd.,
Jiangbei District, Chongqing 400000, P.R. China

https://www.moonsindustries.com/
E-mail:ama-info@moons.com.cn

• All the specifications, technical parameters of the products provided in this catalog are for reference only, subject to change without notice.
For the latest details, please contact our sales department.

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